1. Field of the Invention:
This invention relates to belts for various components of paper making machines which carry and protect the paper as it passes through pressure nips and then gently release the paper. Specifically, the invention deals with paper supporting and conveying belts for components of paper making machinery which are formed from a woven fabric endless loop blanket spray-coated on one or both sides with a urethane coating which impregnates and seals the blanket and having pores providing a finished paper receiving surface with good paper release properties.
2. Prior Art:
Hertofore paper supporting belts for paper making machinery were provided in the form of felted fiber or plastics material blankets such as rubber and the like. In those instances where the plastics material blanket contained a fabric, the plastics material was applied by doctoring a flowable plastics formulation onto the fabric and then curing the coated fabric to form a dense coating free from voids presenting a smooth continuous paper receiving surface. As these belts convey the paper through pressure nips, they are subject to very heavy loads and they must be rigid enough so that they will not crush under the loads and yet pliable enough to wrap around rolls and the like. The necessary pliability could heretofore only be obtained by controlling the plastics material formulations so that they cure to a relatively soft resilient condition that would flow and flatten under nip loads to shift and crush the paper. Further, desirable high nip pressures could not be tolerated.
It would then be an improvement in this art to provide relatively hard and firm but pliable belts conveying paper through high pressure nips of paper machine components with pores or voids in the belts controlled in size to produce desired resilience and paper receiving surfaces which freely release the paper after the pressure nip treatment.